renovate: Update actions/checkout action to v4 (#11)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/go.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Check out code into the Go module directory
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Go
         uses: actions/setup-go@v3